I have read the legislation myself and provided some comments to one of the first media reports that broke the story around expectant mothers. My reading of the legislation, Bill C-13 that created the CERB, is that it does not exclude expectant women. It does contain a provision that says you cannot simultaneously claim maternity or parental and CERB benefits, but it also does acknowledge those same benefits as contributing to the minimum $5,000 of work income to qualify. It seems to me the legislation does anticipate there might be some workers who are in fact pregnant or have had children, and they still require the CERB.
The reports I have heard have included mixed messages from Service Canada personnel when they're called. I think that individual Service Canada officers are no doubt trying to do their best, and that with exceptional cases there is no doubt confusion as to what the exact rules are. To some degree the answer you get might depend on the time of day you call and who happens to be on duty that day. That's why having clarity and having access to additional and local support to problem-solve will always be important in my view, no matter the kinds of programs government is developing.